diff options
Diffstat (limited to 'synapse/api/auth.py')
| -rw-r--r-- | synapse/api/auth.py | 100 |
1 files changed, 58 insertions, 42 deletions
diff --git a/synapse/api/auth.py b/synapse/api/auth.py index 69b3392735..a99986714d 100644 --- a/synapse/api/auth.py +++ b/synapse/api/auth.py @@ -39,6 +39,9 @@ AuthEventTypes = ( EventTypes.ThirdPartyInvite, ) +# guests always get this device id. +GUEST_DEVICE_ID = "guest_device" + class Auth(object): """ @@ -51,17 +54,6 @@ class Auth(object): self.store = hs.get_datastore() self.state = hs.get_state_handler() self.TOKEN_NOT_FOUND_HTTP_STATUS = 401 - # Docs for these currently lives at - # github.com/matrix-org/matrix-doc/blob/master/drafts/macaroons_caveats.rst - # In addition, we have type == delete_pusher which grants access only to - # delete pushers. - self._KNOWN_CAVEAT_PREFIXES = set([ - "gen = ", - "guest = ", - "type = ", - "time < ", - "user_id = ", - ]) @defer.inlineCallbacks def check_from_context(self, event, context, do_sig_check=True): @@ -685,31 +677,28 @@ class Auth(object): @defer.inlineCallbacks def get_user_by_access_token(self, token, rights="access"): - """ Get a registered user's ID. + """ Validate access token and get user_id from it Args: token (str): The access token to get the user by. + rights (str): The operation being performed; the access token must + allow this. Returns: dict : dict that includes the user and the ID of their access token. Raises: AuthError if no user by that token exists or the token is invalid. """ try: - ret = yield self.get_user_from_macaroon(token, rights) - except AuthError: - # TODO(daniel): Remove this fallback when all existing access tokens - # have been re-issued as macaroons. - if self.hs.config.expire_access_token: - raise - ret = yield self._look_up_user_by_access_token(token) - - defer.returnValue(ret) + macaroon = pymacaroons.Macaroon.deserialize(token) + except Exception: # deserialize can throw more-or-less anything + # doesn't look like a macaroon: treat it as an opaque token which + # must be in the database. + # TODO: it would be nice to get rid of this, but apparently some + # people use access tokens which aren't macaroons + r = yield self._look_up_user_by_access_token(token) + defer.returnValue(r) - @defer.inlineCallbacks - def get_user_from_macaroon(self, macaroon_str, rights="access"): try: - macaroon = pymacaroons.Macaroon.deserialize(macaroon_str) - user_id = self.get_user_id_from_macaroon(macaroon) user = UserID.from_string(user_id) @@ -724,11 +713,36 @@ class Auth(object): guest = True if guest: + # Guest access tokens are not stored in the database (there can + # only be one access token per guest, anyway). + # + # In order to prevent guest access tokens being used as regular + # user access tokens (and hence getting around the invalidation + # process), we look up the user id and check that it is indeed + # a guest user. + # + # It would of course be much easier to store guest access + # tokens in the database as well, but that would break existing + # guest tokens. + stored_user = yield self.store.get_user_by_id(user_id) + if not stored_user: + raise AuthError( + self.TOKEN_NOT_FOUND_HTTP_STATUS, + "Unknown user_id %s" % user_id, + errcode=Codes.UNKNOWN_TOKEN + ) + if not stored_user["is_guest"]: + raise AuthError( + self.TOKEN_NOT_FOUND_HTTP_STATUS, + "Guest access token used for regular user", + errcode=Codes.UNKNOWN_TOKEN + ) ret = { "user": user, "is_guest": True, "token_id": None, - "device_id": None, + # all guests get the same device id + "device_id": GUEST_DEVICE_ID, } elif rights == "delete_pusher": # We don't store these tokens in the database @@ -750,7 +764,7 @@ class Auth(object): # macaroon. They probably should be. # TODO: build the dictionary from the macaroon once the # above are fixed - ret = yield self._look_up_user_by_access_token(macaroon_str) + ret = yield self._look_up_user_by_access_token(token) if ret["user"] != user: logger.error( "Macaroon user (%s) != DB user (%s)", @@ -798,27 +812,38 @@ class Auth(object): Args: macaroon(pymacaroons.Macaroon): The macaroon to validate - type_string(str): The kind of token required (e.g. "access", "refresh", + type_string(str): The kind of token required (e.g. "access", "delete_pusher") verify_expiry(bool): Whether to verify whether the macaroon has expired. - This should really always be True, but no clients currently implement - token refresh, so we can't enforce expiry yet. user_id (str): The user_id required """ v = pymacaroons.Verifier() + + # the verifier runs a test for every caveat on the macaroon, to check + # that it is met for the current request. Each caveat must match at + # least one of the predicates specified by satisfy_exact or + # specify_general. v.satisfy_exact("gen = 1") v.satisfy_exact("type = " + type_string) v.satisfy_exact("user_id = %s" % user_id) v.satisfy_exact("guest = true") + + # verify_expiry should really always be True, but there exist access + # tokens in the wild which expire when they should not, so we can't + # enforce expiry yet (so we have to allow any caveat starting with + # 'time < ' in access tokens). + # + # On the other hand, short-term login tokens (as used by CAS login, for + # example) have an expiry time which we do want to enforce. + if verify_expiry: v.satisfy_general(self._verify_expiry) else: v.satisfy_general(lambda c: c.startswith("time < ")) - v.verify(macaroon, self.hs.config.macaroon_secret_key) + # access_tokens include a nonce for uniqueness: any value is acceptable + v.satisfy_general(lambda c: c.startswith("nonce = ")) - v = pymacaroons.Verifier() - v.satisfy_general(self._verify_recognizes_caveats) v.verify(macaroon, self.hs.config.macaroon_secret_key) def _verify_expiry(self, caveat): @@ -829,15 +854,6 @@ class Auth(object): now = self.hs.get_clock().time_msec() return now < expiry - def _verify_recognizes_caveats(self, caveat): - first_space = caveat.find(" ") - if first_space < 0: - return False - second_space = caveat.find(" ", first_space + 1) - if second_space < 0: - return False - return caveat[:second_space + 1] in self._KNOWN_CAVEAT_PREFIXES - @defer.inlineCallbacks def _look_up_user_by_access_token(self, token): ret = yield self.store.get_user_by_access_token(token) |